Introduction
The South American driftwood-catfishes, especially the smaller
species of the genus Centromochlus, are interesting aquarium
fish. In particular, Centromochlus perugiae attracts
attention.

Centromochlus perugiae was described in 1882 by Steindachner
in the Anzeiger der Akademie der Wissenschaften Wien. It keeps
its original placement. One year after the first brief description,
a detailed description followed, with "n. sp." in the
title, which may lead to the assumption that the species was
described
in 1883. The type locality is Canelos, in Ecuador. In 1945 Fowler
described the species Centromochlus altae from Colombia
(Morelis,
Rio Caqueta System), which he distinguished from C. perugiae
mainly by the different coloration ("These are shown as
greatly
differing in detail of the large black blotches, which are also
extended on the caudal and lower flank"). Mees (1974) commented
on this as follows: "There is no doubt in my mind that T.altae
is very closely related to C. perugiae, of which in
future
it will probably have to be regarded as a subspecies, but at
the
same time the differences in colour-pattern are so marked that
is certainly a valid form." Centromochlus altae has
indeed been a
synonym of C. perugiae. The distinction between the
two
species based on coloration wasn't considered valid, since the
color pattern
varies from "densely dotted" to "widely netted"
even in one population. Also the basic background color can vary
from yellowish, even bluish (Vierke 1983), to white. If and how
far the coloration extends to the caudal fin also depends on
the
individual and widely varies in one population. Included in the
genus Tatia for a long time, the species was
moved
to the genus (Soares-Portes 1998)
although the type species
of the genus , C. heckelii, differs
considerably in several points from the smaller species, like
C. perugiae.

Centromochlus perugiae, from Steindachner 1883

Centromochlus altae, from Fowler 1945

Natural Habitat
Seidel
caught C. perugiae in Peru near Pucallpa in creeks and rivers
at 24-30º, at pH ranging from 4.9 to 8.0 in white and clear water.
The conductivity ranged from 10µS to 160µS. At one locality
he found some specimens that looked like C. perugiae and some
that looked like C. altae. They hid during daylight in knotholes
and similar structures (Seidel pers. comm. and Seidel 1997).

SexingCentromochlus perugiae can be easily sexed by looking at the anal fin. The color pattern, however does not give any hint which sex the fish belongs to.

Male's anal fin

Female's anal fin.

Aquarium careT.
perugiae is nocturnal, but soon after the light is turned off the
fish leave their hiding places (especially when being fed) and are very
lively. These small chubby catfish suddenly start catching food handily
in the strongest current.

If one considers the wide distribution and the different water-types
of the species habitats, it is clear that temperature and water values
(pH, conductivity...) aren't important for aquarium care. Much more
important is clear (non-polluted) water with a shallow to strong current.
Even here C. perugiae proves adaptable (if one does not consider
breeding).

Bamboo and plastic tubes are suitable as hideouts, but other hollows
are also accepted. The Centromochlus wedge themselves in the
hideouts with the pectoral and dorsal spines and are very difficult
to get out should they need to be relocated.
In darkness they leave their hideouts and start catching small water
animals. Mosquito larvae, insects etc. are part of their natural diet.
They are mainly caught at the water's surface, which shows that this
species is clearly surface oriented. Hence white mosquito larvae (alive
or frosted) are a convenient food. Drosophila are also eaten with much
gusto. When feeding in darkness, the Centromochlus soon leave
their hideouts and start swimming fast at the water surface, eating
one larvae after another. They are glutons, and one should feed with
caution, since they tend to fatten easily.

What makes C. perugiae especially interesting for aquarium
care, in addition to the attractive coloration and the small size, is
the (compared to other Auchenipterids) relative ease of breeding.

BreedingSoares-Porto (1998) assumed, because of the structure
of the male anal fin, that C. perugiae does not use internal
fertilization. However, aquarium observations showed that isolated females
lay fertilized eggs. The females spawn in their hideouts (mine prefer
PVC tubes, 1.5cm in diameter) up to 100 eggs that expand to ~4mm. The
eggs are insensitive to fungi, and the fertilization rate is mostly
near 100%. If one doesn't have any success breeding the fish because
they don't spawn, intensifying the current and changing water more frequently
may help bring success.

The females usually guard the eggs until they hatch. However, in my
tanks the eggs are normally thrown out of the tubes before they hatch.
Luckily, hatching the eggs in a separate container isn't much of a problem.
I use small Savic Plexiglas tanks, which I direct air into from a 6mm
airline.

The freshly hatched fry have a very large yolk sack. Right after the
fry hatch, I move the larvae into a 50x30x30cm tank. The tank is heated
by an aquarium heater that brings the water to 25ºC, and the water
is filtered by a very large air driven sponge filter. Three to four
days after hatching, the larvae start to show some melanopores. Six
days after hatching, the young fish start to feed.

I start feeding them with Artemia naupli and microworms (Panagrellus
redivivus). After about one week I feed chopped frozen food (Artemia,
black mosquito larvae, bloodworms), and about one month after spawning,
I feed more frozen food and start feeding some flake food given on the
water surface. Little more than one month after spawning the frozen
and flake food replace the Artemia naupli and the microworms totally.
My Centromochlus perugiae (adults and young fish) only feed
at night, and only when being very hungry (for example after days of
fasting) do they feed during the day. I feed the young fish once a day
after the tank lights are switched off. When feeding until they can
barely eat more is sufficient. Adolescent C. perugiae eat oodles
of food, so one should not worry too much about overfeeding. Heavy feeding
also means frequent water changes, so I change about 50% every three
to four days. If you have very few fish to raise, you can feed them
by catching and relocating them into a small glass and feed there. That
does not bother the fish at all, and they feed comfortably until their
stomachs can't take any more food. I did this with the first single
C. perugiae fry I discovered.

Young C. perugiae are as photophobic as the adults, so it is very
important to offer adequate hiding places. It is interesting to note
that young C. perugiae are even more surface oriented than
the adults. Until an age of 3 months young C. perugiae don't
accept any hideouts near the ground. Riccia fluitans is very
suitable, and young fish like to hide in it. When I started breeding
C. perugiae, the tanks I raised the young in did not contain
any Riccia. The few day old Centromochlus swam, scared
up by a water change, continuously in a corner of the tank until exhaustion
or the light was switched off, trying to hide. Additionally, they like
to hide in the grooves of a large sponge filter (see photo to side).

Young C. perugiae have a truncate caudal fin (see below), that
makes them look like tiny Trachelyopterus. About 50 days after
hatching the black-spot pattern becomes visible, and the caudal fin
gains its final forked form.